Automatic coin weighing machine



March 11, 1958 M L, KUDER ET AL 7 2,826,079

AUTOMATIC COIN WEIGHING MACHINE Fiied Oct. 22, 1954 2 Sheets-Sheet 1 INVENTOR Mz'lfon LKuder' Eruzh [Pa/asky Saul I?v Gi/ford BY Maum'cel. Graze/104912 flax 'T'TORNEY March 11, 1958 M. 1.. KUDER ET AL AUTOMATIC com WEIGHING MACHINE Filed Oct. 22, 1954 2 Sheets-Sheet 2 INVENTORS flYz/zon L Kuder froth [.Pa/asky 5041! X. Gil/0rd Mao/"ate L Greenouyh ATTORNEY Hyattsv lle, and Maurice Li. .Gr mu h;.Silv r prina..

Md and Saul R, Gilfordgpherlin ohio, assignors to the United States of America as represented by the Secretary of Commerce Application October 22, 1954, Serial No. {6551,2444

7 Claims.- (Cl; 73 -432) Th s invention,- rel t s. t a. maehinetto :w i'shinst: itiul -r bj and, m e th t rlw q; an; automati Un ed S ter Peseta m c a Q m ei ing machine espe ally des ned for useinthemintingtofijcoinsj,i

The weighing system now used by the S5; Dopamment ofthe, Treasury for'weighing coinsconsistszin dr pping, a. coin, in o b et, suspended; from. the; beam-of an; analytical; balance and, allowing.v the beam to; .come

t rest- T beamis henclatnnedinto wstation y 1 ti rr and the wini ei cted intoei h na;hiahonalow chute repr senting an; underweight: or overweighttcoin with-respect to the: standard, coin; againstgwhich-witl is measured. This; proc s a es about: four; onds; A

limitation n; ncreas ng he response speed. of: hist ype of. bal n e is: he ratio; hetw enzthe-ma s: i he; heath: and

I he comp ra iv yll; di rencein wei htt etw en the twotcoins since; the. small difierence in mass; of thecoins will; not acc le a e he-large mass.v of the beam; ve y" rapidly.

The pr sent inv ntion comprises a tally, automatic; mac ine for w igh ng co ns rvan va h machine o he pres t n e i r can igh:.-and sort 1.83 091. coins p r our-with n. acc a y of one-four h 051 13 percent nreans for .a ltomatioally, weighing: and; sorting-circula objects. Another object of; this. invention-is 1 to provide improve means for; automatically weighing andsorting eoinsty Another object; ofithis invention is to providemcans fprautomatieally weighing coinsat. a high rate of speed.

A. further; object is to providemeans for weighing coins witha eh eg e of acc r cy A, finali objectiof thisinventionis to providemeanstfor Weighing coins independent of all, the physicalpropcrties of thecoins except the coin diameters.

The system is more fully explained with reference: to the. accompanying drawingsinwhich:

Fig. 1 shows a diagram of the fundamental physical elements of theweighingsystem;

2 shows a yn mi torce diagram at he weighin sy tem;

Fig 3 shows the overall physical embodimentofqthe A frameassociated with the coin weighing machine;

Fi .4 ShQW .6..-, o.werportion o the assemb yt Fig 5 shows an enlarged view-of the;bottom-halfof the coin wheel.

The coin weighing machine,v according to, the vpresen n en ons-r W ighs: coins y: me suring e e ee Q laalance; imparted; to a, rapidlyrevolving-l flywheel into -w hi ch;two; coins,,i. eithe rstandard-i anclathetoneto be V weighedg have been placed; It initially the flywheel was 2,826,079 fiatent d Mar. 11, 1958 v 2: a precisely balanced; the difierence inweight between the two; coins will displace the center of massslightly from the g eornetric center-of the wheel. Detection of this displacement provides the basis for measuring the weight-of the-coi-n. A unique method is included in the machine for injecting; the coin into the rapidly moving flywheel and removing the coin after it; has been weighed. Sorting of coins into good and bad 'categories is accomplished through suitable circuitry and structure which permits precise determination of theangular position of the wheel at which the coin is to be removed so that it will falhinthe propercontainer.

In Fig. 1 asshown; the-systemi's essentially a pendulum the principal mass of which is concentrated'i'n a balanced flywheel henceforth referred to-as -coinwheel .l which ispreterably approximately seven inches in difulcrum-for the shait 2 leaving itfree to swing in'any directiom- Above the gimbal mount 3 and not-shown is a D.'-C. motor which turns the coin wheel latan angul'ar velocit-y w-of- 300011. P.-M-. The shaft} isoff such length that' the natural pendulum period of the shat-t and wheel is much longer than the period of vibration establishedby therotationalg motion of wheel 1: Thus the vibrational effects due to the wheel 1 are effectively independent of the pendulum action of the wheel and-shaft, and: the rotation of the center of mass; ofthe wheel 1 about its geometrie center takes; place as though the wheel werea body revolvingintree space.

Elements 4 and; 5 represent the standard coin and the win of; unknown weigh-tdisposed diametrically opposite from each other along an imaginary diameter line of the coin wheell and atequal distances from the center of the wheel. A mutual inductance micrometer is shown at 6 which 'serves to sense the magnitude offthe lateral displacement of shaft 2 dueto the rotation of coins of unequalweight, I

A better understanding of the principle involved can be had from Fig. 2 which shows a force diagram ofthe coin wheel- 1 in an instantaneous steady states rotational position assuming the mass C of coin 4- to be greater than themass C of coin- 5 Equating; the forces on each side of the center of rota-tion:-

( MwArE aC )R This may be written as (a: Ar=% c a0 SintwMw, and Rare constant:

( M rc -c Where geometric center It can be seen from the equations that the distance the center of mass of the wheel shifts is directly proportional to the difference between two weights, one of which is the known weight-of astandard coin; ;Obvi ouslyif C were assumedfto be less than C rather than" greater, .the center of mass shift would be in the opposite direction and the distance Ar would have the opposite sign.

By rotating the wheel 1 at 300011. P;.'M. with the coins 4 and 5 about two and one-half inches from thecenter of the wheel, an acceleration of nearly 500 g. is imparted to the coins. This magnifies the small weight differential between the coins 500-fold. The vector product of the large synthetic acceleration and the small differential mass is the force which causes the wheel toraccelerate rapidly into a new orbitabout its new center of mass whenever a coin of unknown weight is placed in ewh t Within six wheel revolutions'after a new coin is placed on the wheel the initial transient disturbance resulting from loading the new coin intothe peripheryof the wheel while it is rotating is damped down. Sincethe wheel is revolving at 3000 R. P. M., these six revolutions take only 0.12 second. The subsequent detectionof the constant amplitude of vibration that determines the difference in weight between the two coins is made during the two following revolutions. A total of ten revolutions is allowed for the complete weighing cycle; thus five coins can be weighed each second. 7

Fig. 3 shows the physical construction of the wheel supporting structure and associatedelements. At 7 appears the D. C. drive motor for imparting rotary motion to shaft 2. The motor fuse box is shown at 8. The means for providing the damping referred to above takes the form of two sets of damping bumpers 9 adjacent the lower portion of shaft 2. As can be seen the entire unit is supported by a metallic A-frame indicated generally at 11.

Fig. 4 illustrates the lower portion of the A-frame support showing the relation of the coin wheel 1 to the A- frame mechanism and associated elements.

An electronic mutual-inductance micrometer 6, Figs.

1 and 4, of the type described in an article in Electronics entitled, Technical Data on Electronic Micrometers, vol.

20, pages 172480, November 1947, placed near the wheel hub detects the lateral oscillations of the pendulum shaft. This device is an extremely sensitive transducer which can determine a change in length as small as 50 .microinches and can accurately measure the few thousandths of an inch displacement in the weight-indicating vibration. The transducer consists of two coplanar, coaxial coils wound on a dielectric core. The primary coil is energized from a regulated R.-F. source whose frequency is much higher than the wheel vibration frequency. The mutual-inductive coupling between the primary and secondary varies as a nearby conducting material-i. e. the wheel hubmoves toward or away from the coil assembly. When the wheel vibrates, the secondary coil generates a modulated A.-C. signal whose period is equal to one revolution of the wheel. In the present weighing machine the transducer'with its regulated power supply and simple amplifier produces a signal of relatively large amplitude which is linearly proportional to the departure of the coin from the nominal weight. The

response speed is more than adequate to meet the requirements of this use.

Referring again to Fig. 4 entrance chute 12 is provided for the passage of the coins 5 to be weighed. The coins are arranged edge to edge along the chute as shown and are successively moved along by a reciprocating hydraulic ram with a stroke length equal to the diameter of one coin. The hydraulic ram driving means is not illustrated and forms no part of the present invention.

A solid dielectric block 13 is slotted to receive the end of chute 12. Chute 12 extends into block 13 to point 21 where it ends. The coins then pass along'apassage 22 in block 13 and the rightmost coin abuts against semicircular end 23 of passage 22. The end 23 of passage 22 is of semicircular shape to avoid excessive bouncing of the coins as they are forced against the end of the passage. Chute 12 and passage 22 provide room for eleven coins placed edge to edge in the embodiment shown. As each successive coin is inserted into the wheel 1 an additional coin is placed in the entrance of chute 12 by any suitable automatic feeding means (not shown).

At 24 is shown a cup-shaped ferrite core completely enclosing a plurality of solenoid windings 26 of suitably sized wire, for example, number 26 enameled wire. Core 24 includes central post 25 around which windings 26 are wound.

The entire solenoid assembly 24, 25, 26 is coated over its upper surface with a thin coating 27 of dielectric coating which may be of the same material as block 13.

'It should be noted that the only metallic objects near core 24 are the coins Stravlingalong passage 22 so that the magnetic field produced by solenoid 26 utilized to insert each coin is not weakened by the presence of any nearby metal.

In operation the coin to be weighed passes along chute 12 into the dielectric block 13. Here solenoid 26 injects the coin into the wheel 1 through a coin entrance hub 14. The coin is weighed and then passes out exit port 16.

The coin to be weighed and the standard coin lie on a straight line which passes through the geometrical center of the wheel 1; If the coin to be weighed is heavier or lighter than the standard, the center of mass of the pendulum moves along this straight line to one side or other of the geometric center of the wheel. Depending upon whether the coin is lighter or heavier than the the coin in the wheel passes a given point. As can be 'seen in Fig. 3, three mirrors 17, shown in the drawings as a single mirror, mounted on the'rotating shaft 2 at slightly different angles with'respect to the shaft axis reflect beams of light from light source 18 onto three photocells 19, thereby generating an electrical pulse each time the coin passes a given point corresponding to the position of each mirror on the shaft. This direct and reflected light passes through light ports 20. The photocell signals coincide with either a positive or negative signal from the micrometer transducer 6 once each revolution of the wheel 1, and the combination of these signals indicates whether the coin is lighter or heavier than the standard. I

Fig. 5 is an enlarged view of the top of the lower section of coin Wheel 1. On one side of the wheel is shown the standard weight 4 while directly opposite the standard in weighing position is the unknown coin S. The removable center core is shown generally at 31 including a slightly eccentric entrance port 32. A removable clip 34 has a physical detent 36 in which coin 5 is held by centrifugal force. Upon ejection the coin 5 passes over retaining hump 37 and out the exit port 16. Holes 38 are for the purposes of inspection while holes 39 and screws 41 provide means to adjust the balance "of the wheel.

to the solenoid 26, produces a powerful eddy-current magnetic repulsion field between the coin and the core, thereby lifting the coin into the hole. The axis of the hole in the hub is inclined 'at a small angle to the axis of the rotating spindle and directs the coin into a position that is slightly away from'the geometric center of the flywheel.

Thereafter, centrifugal force causes the coin to move into the pocket at the periphery of the wheel as shown in the .figure. The .newcoinimParts its kinetic-energy to the weighed coin that is already in the pocket, thereby forcing this coin off the wheel. By properly controlling the time at which the new coin is inserted into the wheel, the eject phase position is so chosen that the weighed coin may be cast into an accept or reject receptacle. The timing is electronically determined by the weight of the coin in the wheel.

The strobe light 32 shown in Fig. 4 is used in conjunc tion with holes 39 and screws 41 to balance the wheel.

If two standard coins are placed in the flywheel, the only source of vibration is the unbalance of the wheel itself. The mutual-inductance micrometer 6 detects this unbalance, and a photocell energized by a light beam reflected from one of the mirrors 17 on the shaft 2 assists in determining the phase of the unbalance. The electronic combination of these two signals operates a strobescope including strobe light 32 which illuminates only the heavy portion of the wheel. Degree markings on the edge of the wheel identify the heavy position, and 'adjustments of screws 41 or if necessary drilling holes such as holes 39 permit alteration of the weight distribution. Usually only one or two trials are necessary to restore the wheel to precise balance.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of invention as defined in the appended claims.

What is claimed is:

1. A precision weighing device for accurately comparing the weight of an unknown circular object with a standard weight comprising means for rotating said unknown object and said standard weight about a vertical axis perpendicular to the midpoint of a line joining the centers of said object and said standard weight, means for determining the comparative weight of said object by detecting the amplitude of the variation of the center of mass of the combination of said object and said standard weight from said midpoint and means for removing said unknown object from said rotating means without alter ing the rotational velocity thereof.

2. A precision weighing device for accurately comparing the weight of an unknown circular object with a standard weight comprising means for rotating said unknown object and said standard weight about a vertical axis perpendicular to the midpoint of a line joining the centers of said object and said standard weight, means for determining the comparative weight of said object by detecting the amplitude of the variation of the center of mass of the combination of said object and said standard weight from said midpoint, and means for removing said unknown object from said rotating means and inserting a second circular object to be weighed into said rotating means without altering the rotational velocity thereof.

3. A precision weighing device for accurately comparing the weight of an unknown circular object with a standard weight comprising a rotating shaft, wheel means including means for supporting said object and said standard weight connected to one end of said shaft, means for detecting the displacement amplitude of said shaft caused by a difference in weight between said object and said standard weight and means for simultaneously removing said object from said wheel means and inserting a second circular object to be weighed into said wheel means without altering the rotational velocity thereof.

4. A precision weighing device for accurately comparing the weight of an unknown circular object with a standard weight comprising a vertical rotating shaft, wheel means including means for supporting said object and said standard weight coupled to the lower end of said shaft, means for determining the comparative weight of said object by detecting the amplitude displacement of said shaft, and means for simultaneously removing said object from said wheel means and inserting a second circular object to be weighed into said wheel means without altering the rotational velocity thereof.

5. A precision weighing device for accurately comparing the weight of an unknown coin with respect to a standard weight comprising a double gimbal mounted vertical shaft, means for rotating said shaft at a constant velocity, a wheel connected to the lower end of said shaft, said wheel including means for supporting said coin and a standard weight on opposite sides along a diameter and near the periphery thereof, means for detecting the amplitude of the lateral displacement of said shaft occasioned by a difference in weight between said coin and said standard weight and means for removing said coin from said wheel and inserting a second coin to be weighed without altering the rotational velocity of said wheel.

6. A precision weighing device for accurately comparing the weight of an unknown coin with respect to a standard weight comprising a double gimbal mounted vertical shaft, motor means coupled to the upper end of said shaft for driving said shaft at a constant angular velocity, a weighing wheel connected to the lower end of said shaft, a standard weight supported in said wheel near the periphery thereof, means for retaining an unknown coin near the periphery of said wheel and displaced from said'standard weight, means for detecting the relative amplitude of the lateral displacement of said shaft caused by a difference in weight between said coin and said standard weight, means for injecting a second coin to be weighed into the central portion of said wheel, said wheel including means for guiding said injected coin under the influence of centrifugal force into said unknown coin whereby the energy of said injected coin is transmitted to said unknown coin ejecting it from said wheel.

7. A weighing device as defined in claim 6 in which said injecting means includes an electromagnetic solenoid for applying an injecting repulsion force to said second com.

References Cited in the file of this patent UNITED STATES PATENTS 294,363 Butler Mar. 4, 1884 2,037,443 Van Degrift Apr. 14, 1936 2,629,490 Bailey Feb. 24, 1953 FOREIGN PATENTS 71,073 Germany Sept. 22, 1893 

